T. Yamagami’s research while affiliated with Japan Aerospace Exploration Agency and other places

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Publications (288)


Figure 1: Cross-sectional views of the BESS-Polar II payload. 
Figure 3: Measured ratio of 2 H/ 1 H with BESS-Polar II (black filled circles). Measurements are compared with IMAX-92 [13] (open circles), BESS-93 [5] (open squares), BESS-00 [6] (open diamonds) and PAMELA [15] (open stars and crosses). GALPROP [16], in which the proton fusion process was implemented and isotope production cross sections were updated (c.f. [17]), is employed for comparison using stochastic reacceleration [18] (solid lines) at different solar modulation parameters of 450, 700 and 1200 MV (force-field model). 
Precise Measurements of Hydrogen and Helium Isotopes with BESS-Polar II
  • Conference Paper
  • Full-text available

July 2017

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84 Reads

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2 Citations

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K Abe

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H Fuke

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K Yoshimura

A precise knowledge of cosmic-ray hydrogen and helium isotopes provides important information to better understand Galactic cosmic-ray propagation. Deuteron and helium 3 species are mainly secondary particles created by the spallation of primary proton and helium 4 particles during their propagation in the Galaxy. Secondary-to-primary ratios thus bring direct information on the average amount of material traversed by cosmic rays in the interstellar medium. The Balloon-borne Experiment with Superconducting Spectrometer BESS-Polar II flew over Antarctica for 24.5 days from December 2007 through January 2008, during the 23rd solar cycle minimum. The instrument is made of complementary particle detectors which allow to precisely measure the charge, velocity and rigidity of incident cosmic rays. It can accurately separate and precisely measure cosmic-ray hydrogen and helium isotopes between 0.2 and 1.5 GeV/nucleon. These data, which are the most precise to date, will be reported and their implications will be discussed.

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Measurements of cosmic-ray proton and helium spectra from the BESS-Polar long-duration balloon flights over Antarctica

June 2015

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374 Reads

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103 Citations

The Astrophysical Journal

The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in December 2004 and December 2007, at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2-160 GeV and helium nuclei 0.2-80 GeV/nucleon. The corresponding magnetic rigidity ranges are 0.6-160 GV for protons and 1.3-160 GV for helium. These spectra are compared to measurements from previous BESS flights and from AMS-01, ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.3 GV to 160 GV and compare to ratios from PAMELA and AMS-02.


Measurements of cosmic-ray proton and helium spectra from the BESS-Polar long-duration balloon flights over Antarctica

June 2015

The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in December 2004 and December 2007, at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2-160 GeV and helium nuclei 0.15-80 GeV/nucleon. The corresponding magnetic rigidity ranges are 0.6-160 GV for protons and 1.1-160 GV for helium. These spectra are compared to measurements from previous BESS flights and from ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.1 GV to 160 GV and compare to ratios from PAMELA and AMS-02.


MHD wave characteristics inferred from correlations between X-rays, VLF, and ULFs at Syowa Station, Antarctica and Tjörnes, Iceland (L∼6)

June 2014

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57 Reads

Earth Planets and Space

The Polar Patrol Balloon No. 6 (PPB#6) observed quasi-periodic pulsations of bremsstrahlung X-rays (E 30∼120 keV) in the daytime of 0855 UT (0914 MLT) ∼ 1630 UT (1614 MLT) on January 5, 1993, near Syowa Station, Antarctica (L∼6). The X-ray pulsations near the noon (1208:00 UT (1216 MLT) ∼ 1225:04 UT (1232 MLT)) include a period of about 260 sec, which corresponds to Pc 5 magnetic pulsations. It was found that at Syowa Station and Tjörnes, Iceland, which are both pair locations of the geomagnetic conjugacy, the X-ray pulsations are in correlation with the ULF-D pulsations. Also the Tjörnes VLF (2 kHz) pulsations correlated well with the X-ray pulsations of the period corresponding to Pc 5. It is probable that the VLF- and ULF-associated X-rays or precipitating energetic electrons in the vicinity of the L ∼ 6 shell are in synchronization with the electron-cyclotron resonance. Lastly, the so-called ballooning-mirror instability (the BMI) is a candidate to explain the compressional MHD waves that occur during the short time interval (1216 MLT ∼ 1232 MLT) in which the experimental results were interpreted.


Time variations of cosmic-ray helium isotopes with BESS-Polar I

May 2014

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21 Reads

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10 Citations

Advances in Space Research

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is configured with a solenoidal superconducting magnet and a suite of precision particle detectors, including time-of-flight hodoscopes based on plastic scintillators, a silica-aerogel Cherenkov detector, and a high resolution tracking system with a central jet-type drift chamber. The charges of incident particles are determined from energy losses in the scintillators. Their magnetic rigidities (momentum/charge) are measured by reconstructing each particle trajectory in the magnetic field, and their velocities are obtained by using the time-of-flight system. Together, these measurements can accurately identify helium isotopes among the incoming cosmic-ray helium nuclei up to energies in the GeV per nucleon region. The BESS-Polar I instrument flew for 8.5 days over Antarctica from December 13th to December 21st, 2004. Its long-duration flight and large geometric acceptance allow the time variations of isotopic fluxes to be studied for the first time. The time variations of helium isotope fluxes are presented here for rigidities from 1.2 to 2.5 GV and results are compared to previously reported proton data and neutron monitor data. Published by Elsevier Ltd. on behalf of COSPAR.


Spectra of H and HE measured in a series of annual flights

July 2013

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16 Reads

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11 Citations

Advances in Space Research

We have obtained the absolute spectra of H and He by analyzing data collected by a series of annual flights of the Balloon borne Experiment with a Superconducting solenoid Spectrometer payload. This instrument is configured with a cylindrical magnet, a Time-of-Flight system, a set of cylindrical multiwire drift chambers inside and outside the magnet, and a central tracking device Jet chamber. The analysis involves Monte Carlo simulations of the effective geometry factor, studies of various efficiencies, and corrections for the ionization energy loss, attenuation and atmospheric secondaries. Variations of the H and He fluxes at different levels of solar modulation are presented.


Cosmic ray 2H/1H ratio measured from BESS in 2000 during solar maximum

January 2013

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31 Reads

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17 Citations

Advances in Space Research

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) was flown from Lynn Lake, Manitoba, Canada in August, 2000, during the maximum solar modulation period, with an average residual atmospheric overburden of 4.3 g/cm2. Precise spectral measurements of cosmic ray hydrogen isotopes from 0.178 GeV/n to 1.334 GeV/n were made during the 28.7 h of flight. This paper presents the measured energy spectra and their ratio, 2H/1H. The results are also compared with previous measurements and theoretical predictions.


Search for cosmic-ray antiproton origins and for cosmological antimatter with BESS

January 2013

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31 Reads

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20 Citations

Advances in Space Research

The balloon-borne experiment with a superconducting spectrometer (BESS) has performed cosmic-ray observations as a US–Japan cooperative space science program, and has provided fundamental data on cosmic rays to study elementary particle phenomena in the early Universe. The BESS experiment has measured the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic origins such as dark matter candidates or primordial black holes, and searched for heavier antinuclei that might reach Earth from antimatter domains formed in the early Universe. The apex of the BESS program was reached with the Antarctic flight of BESS-Polar II, during the 2007–2008 Austral Summer, that obtained over 4.7 billion cosmic-ray events from 24.5 days of observation. The flight took place at the expected solar minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. Here, we report the scientific results, focusing on the long-duration flights of BESS-Polar I (2004) and BESS-Polar II (2007–2008).


Figure 1. Typical configuration of the emulsion chamber in cross-sectional drawing from a side view.
Table 1 : List of balloon flights
Fig. 4.-Total exposure SΩ e T for primary electrons with electron energy.
Figure 9. Primary cosmic-ray electron spectrum observed with emulsion chambers (ECC) compared to recent experiments (DuVernois et al. 2001; Torii et al. 2001; Aguilar et al. 2002; Chang et al. 2008; Ackermann et al. 2010b; Aharonian et al. 2009; Adriani et al. 2011a). The dotted line shows the best-fit power-law spectrum with an index of −3.28.
Observations of High Energy Cosmic-Ray Electrons from 30 GeV to 3 TeV with Emulsion Chambers

October 2012

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103 Reads

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23 Citations

The Astrophysical Journal

We have performed a series of cosmic-ray electron observations using the balloon-borne emulsion chambers since 1968. While we previously reported the results from subsets of the exposures, the final results of the total exposures up to 2001 are presented here. Our successive experiments have yielded the total exposure of 8.19 m^2 sr day at the altitudes of 4.0 - 9.4 g/cm^2. The performance of the emulsion chambers was examined by accelerator beam tests and Monte-Carlo simulations, and the on-board calibrations were carried out by using the flight data. In this work we present the cosmic-ray electron spectrum in the energy range from 30 GeV to 3 TeV at the top of the atmosphere, which is well represented by a power-law function with an index of -3.28+-0.10. The observed data can be also interpreted in terms of diffusive propagation models. The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of cosmic-ray electron sources at distances within ~1 kpc and times within ~1x10^5 yr ago.


FIG. 2. 
Search for Antihelium with the BESS-Polar Spectrometer

March 2012

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100 Reads

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65 Citations

Physical Review Letters

In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4×10(6) |Z|=2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0×10(7) |Z|=2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9×10(-8)} was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0×10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date.


Citations (60)


... Next, we developed a thinner polyethylene ¯lm with a thickness of 3.4 m using metallocene as a catalyst ( Saito et al., 2002). In 2002, a balloon with a volume of 60,000 m 3 made from this 3.4-m- thick ¯lm lifted a 4.6-kg payload to an altitude of 53.0 km, which equaled the world record altitude at the time for an unmanned balloon (Yamagami et al., 2004). We then developed an even thinner ¯lm with a thickness of 2.8 m ( Saito et al., 2006); however, we encountered di±culties when trying to launch balloons made from this ultra-thin ¯lm. ...

Reference:

Recent Highlights of Scientific Ballooning in Japan
Development of the highest altitude balloon
  • Citing Article
  • December 2004

Advances in Space Research

... Based on the feedback from the analysis of the BESS-Polar I data, various improvements were done and many of the detectors and systems were redesigned and re-fabricated both to improve performance and flight duration. A detailed description of the instrument was reported elsewhere [6] [7]. Here major improvements and modifications from BESS-Polar I are highlighted and discussed. ...

BESS-Polar Experiment –Progress and Future Prospect–
  • Citing Article
  • January 2009

Journal of the Physical Society of Japan

... To date, the spectrum [64] (Fig. 6) does not show evidence for the possible appearance of a nearby electron source. Even the anisotropy is claimed to be fully consistent with an isotropic distribution of arrival directions [64]. The BESS-Polar experiment has presented several interesting results, ranging from low energy cosmic ray spectra to spectra of antiprotons and limits to the flux of anti-helium nuclei. ...

Energy spectrum and arrival directions of high-energy electrons over 100 GeV observed with PPB-BETS
  • Citing Article
  • January 2007

... The original BESS-Polar experiment flew over Antarctica in late 2004. The BESS-Polar II experiment collected 24.5 days of Antarctic flight data from December 2007 to January 2008 [241,242]. BESS-Polar II, shown in Fig. 13, consists of a 0.8 T solenoidal magnet, filled by inner drift chambers (IDC) and a jet-type drift tracking chamber (JET), and surrounded by an aerogel Cherenkov counter (ACC) and a time-of-flight (TOF) system composed of scintillation counter hodoscopes. These components are arranged in a coaxial cylindrical geometry, providing a sizeable geometric acceptance of 0.23 m 2 sr. ...

BESS-polar: Search for antihelium
  • Citing Article
  • January 2011

... Notably, the cosmic ray energy spectrum data obtained from the CREME96 model does not distinguish between 3 He and 4 He, necessitating a parameterization of the cosmic ray He spectrum. Measurement experiments pertaining to the 3 He/ 4 He ratio, designated as C, have yielded relatively precise and comprehensive results (Abe et al., 2014;Casolino et al., 2011;Myers et al., 2003;Wang et al., 2002). Tables 1 and 2 present the values of C(M) for solar maximum and C(m) for solar minimum activity periods . ...

Time variations of cosmic-ray helium isotopes with BESS-Polar I
  • Citing Article
  • May 2014

Advances in Space Research

... CRs can also be categorized by their energy levels; for example, low-energy CRs are trapped by the Earth's magnetic field and interact with the upper atmosphere, while high-energy CRs penetrate deeper into the atmosphere and are detectable by ground-based instruments [10,1,4]. Studying cosmic rays allows scientists to gain insights into fundamental processes in the universe, such as the behavior of high-energy particles and the conditions in distant astrophysical objects [11]. ...

Measurements of cosmic-ray proton and helium spectra from the BESS-Polar long-duration balloon flights over Antarctica

The Astrophysical Journal

... The last published antideuteron results relied on the previous BESS flights, which took place between 1997 and 2000, setting an exclusion limit at 95% confidence level of 1.9×10 −4 (m 2 s sr GeV/n) −1 in the range of 0.17-1.15 GeV/n [243]. Extended BESS-Polar II antiproton and the antideuteron analyses are currently ongoing, using the middle-TOF that lowers the energy range to about 100 MeV/n. ...

Search for cosmic-ray antideuterons with BESS-Polar

... The CALorimetric Electron Telescope (CALET) mission aims to reveal high energy phenomena in the universe by space-based observation of the high energy cosmic rays [4]. The detector is intended to be placed on the Japanese Experiment Module (JEM) of the International Space Station (ISS). ...

The CALET instrument for experiment on the ISS

... Open gray right-pointing triangles, diamonds, upward-pointing triangles, circles, downward-pointing triangles, squares, and left-pointing triangles mean observations from Meyer & Vogt (1963), Freier & Waddington (1965), Freier & Waddington (1968), Ormes & Webber (1968), Rygg & Earl (1971), Garrard et al. (1973), and Rygg et al. (1974), respectively. Filled green squares, circles, downward-pointing triangles, upward-pointing triangles, and squares represent proton fluxes observed by LEAP (Seo et al. 1991), MASS (Webber et al. 1991), IMAX (Menn et al. 2000), BESS (Wang et al. 2002;Seo et al. 2001;Shikaze et al. 2007;Abe et al. 2016), and CSES-01 (Bartocci et al. 2020), respectively. Filled gray, sky-blue, pink, and blue circles mean observations from IMP 8, SOHO/EPHIN (Kuhl et al. 2016), PAMELA, and AMS-02, respectively. ...

Spectra of H and HE measured in a series of annual flights
  • Citing Article
  • July 2013

Advances in Space Research

... As a result, the maximum tensile stress of the balloon envelope is σ 2.4 MPa at 23℃ and σ 5.0 MPa at 50℃. Meanwhile, the tensile strength of the balloon envelope was measured as 50-62 MPa at 23℃ and 64-92 MPa at 40℃. 15) Hence, a sufficient margin of safety is secured for the balloon envelope. ...

A challenge to the highest balloon altitude
  • Citing Article
  • February 2012

Advances in Space Research